Mechanism for current limiting circuit breaker



MECHANISM FOR CURRENT LIMITING CIRCUIT BREAKER K. J. STOKES 2 Sheets-Sheet 1' Filad July 16, 1968 5 RE Z m5 WM M m n N m m K M m. mu

A TTORNE V MECHANISM FOR CURRENT LIMITING CIRCUIT BREAKER Filed July 16. 1968 K-. J. STOKES,

m 9 1 aw 2 Sheets-Sheet 2 TRIPPEU' IZZ FIGS

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s W m u m M war w /.M 4 u K w United States Patent U.S. Cl. 335-16 14 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker has a movable contact carried by a contact operating member, a pivotable releasable member, and automatic operating means actuatable by a short circuit normally holding the releasable member in a fixed position. A rapid action circuit opening means is operable rapidly by a short circuit current passing therethrough to effect movement of the contact operating member from closed circuit position to open circuit position. Manual operating means is connected to the contact operating member for effecting movement thereof between closed and open circuit positions through a novel link mechanism including a link member having pivots adjacent the upper and lower ends thereof and means engaging its lower end with the contact operating member for movement axially therewith. The pivots of the link member are movable along arcuate paths extending axially of the contact operating member by the automatic operating means and the manual operating means so as to effect movement of the contact operating member between closed and open circuit positions. In addition, the lower pivot of the link member is movable along its arcuate path by movement of the contact operating member upon actuation of the circuit opening means.

BACKGROUND OF THE INVENTION The increasing use of electric power for various purposes has produced a requirement for electric power supply systems of ever increasing capacity and a concurrent requirement for circuit breakers capable of interrupting the high short circuit currents which can occur in such power systems, Moreover, it has been recognized that it is desirable to prevent the short circuit current from attaining a magnitude during interruption which approaches the prospective short circuit current maximum since even the interrupted short circuit current may cause damage to other circuit components.

As a result there have been developed a number of electric circuit breaker devices employing a current limiting technique to extend the range and capability of contact opening circuit breakers. In such devices, means is provided whereby the contacts may be opened at very high speed upon the occurrence of a short circuit condition, this opening taking place essentially independently of the conventional operating and tripping mechanism. A highly effective current limiting electric circuit breaker of this type is disclosed in Patent No. 3,384,845, I. F. Johnson et al., issued May 21, 1968 and assigned to the same assignee as the present invention.

As disclosed in the aforementionad Johnson et al patent, it is highly desirable to open the contacts of the circuit breaker very quickly after the occurrence of a short circuit condition, thereby drawing the are quickly. As further pointed out in this patent, operation of the movable contact is desirably free from movement of the relatively massive elements of the switching mechanism so that the inertia of the system does not detract from 3,488,609 Patented Jan. 6, 1970 rapid opening. To this end, the Johnson et al. device includes a disengageable coupling between the manual operating mechanism and the contact operating rod.

It is an object of the present invention to provide a novel circuit breaker which is capable of rapidly opening the contacts independently of operation of the manual operating mechanism and which may be simply and economically constructed.

It is also an object to provide such a circuit breaker utilizing a novel linkage permitting rapid movement of the contact operating member and only a portion of the linkage to minimize inertia upon actuation of automatic operating means functioning in response to a short circuit current of high magnitude.

Another object is to provide such a circuit breaker which may be readily assembled and disassembled and which is capable of long lived operation and adapted to facile variation in the magnitude of short circuit current required for automatic operation.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained in an electric circuit interrupter having a casing containing a stationary contact and a movable contact with a contact operating member carrying the movable contact at one end thereof. Means in the casing mounts the contact operating member for movement of the movable contact between closed and open circuit positions, and manual operating means is pivotably mounted in the casing for movement between closed and open circuit positions. A releasable member with a latch portion at one end is pivotably mounted at its other end adjacent the contacts and is pivotable from a normal latched position to a released position. Current responsive means in the housing normally engages the latch portion of the releasable member in the latched position and is operable in response to a predetermined current flowing through the contacts to release the latch portion of the releasable member for pivoting thereof into the released position.

A link member has pivot means adjacent the ends thereof, and means on the releasable member moves the upper pivot means in an arcuate path extending generally axially and rising toward the other end of the contact operating member. Means on the casing moves the lower pivot means of the link member in an arcuate path extending generally axially and rising toward the other end of the contact operating member. Interengaging means provides coupling of the lower pivot means to the contact operating member for axial movement therewith to effect operation thereof between open and closed circuit positions and also enables relative movement therebetween transversely of the contact operating member.

Operating spring means is connected between the manual operating means and either the link member or the means for moving the upper pivot means so as to effect movement of the lower pivot means of the link member and thereby the contact operating member between open and closed circuit positions in response to pivotal movement of the manually operable means between open and closed circuit positions. Both pivot means of the link member are biased toward the contacts in the closed circuit position, and the operating spring means acts on the releasable member through its action on the link member or moving means to which it is attached when the releasable member is released by the current responsive means. In this manner, the releasable member is pivoted to released position and the upper pivot means is moved in the arcuate path away from the contacts. This movement causes movement of the lower pivot means in its arcuate path away from the contacts and thereby produces movement of the contact operating member from the closed circuit position.

Secondary spring means is connected between the link member and a fixed point with respect to the casing and biases the lower pivot means of the link member toward the contacts in the closed circuit position. Cooperating with the contact operating member is rapid acting automatic operating means for moving the contact operating member axially thereof from closed circuit position to open circuit position rapidly upon passage of a short circuit current of predetermined magnitude therethrough. Upon such movement in response to the automatic operating means, the lower pivot means of the link member is moved in its arcuate path away from the contacts and the other end of the link member is pivoted about the upper pivot means without movement thereof in the arcuate path away from the contacts. During such movement of the lower pivot means in its arcuate path, the secondary spring means accelerates the axial movement of the contact operating member into open circuit position in which condition it biases the lower pivot means of the link member away from the contacts.

In the preferred embodiment of the invention, the current responsive means is also actuated by the short circuit current which actuates the automatic operating means. As a result, the latch portion of the releasable member is released and the releasable member then pivots away from the contact operating member. During the pivotal movement, the upper pivot means of the link member is moved in its arcuate path away from the contacts so that both pivot means are ultimately disposed at the end of their arcuate paths away from the contacts. Although the means for moving the pivot means of the link member in arcuate paths may be provided by suitably pivoted upper and lower link elements pivoted thereto, the preferred embodiment utilizes cam surfaces on the releasable member and on the casing to effect such movement.

In order to permit optimum movement of the two pivot means of the link member, one of the two pivot means should be supported so as to be variable in spacing from the other pivot means during operation of the device. In the preferred embodiment utilizing a cam surface portion on the releasable member or cradle, this is conveniently provided by a pin and slot support for the shaft of the cam follower in the link member.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view of an electric circuit breaker embodying the present invention with a portion of the casing and of certain components broken away to reveal internal construction and with the movable elements illustrated in full line in the closed circuit or on condition and with certain of the movable operating elements being shown in phantom line in the magnetically tripped condition;

FIGURE 2 is a fragmentary side elevational view illustrating the movable operating elements of the circuit breaker of FIGURE 1 in the manually operated open circuit or 01f condition;

FIGURE 3 is a view similar to FIGURE 2 illustrating the movable operating elements in the condition assumed upon operation by a sustained short circuit current causing release of the cradle from its initial position shown in phantom line;

FIGURE 4 is a partially diagrammatical fragmentary transverse sectional view of the circuit breaker of FIG- URE 1 generally along the line 44 thereof and with portions of the components broken away to facilitate illustration; and

FIGURE 5 is an exploded fragmentary perspective view of certain of the movable operating parts thereof with a portion of one arm of the body of the operating rod broken away for clarity of illustration.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning first in detail to FIGURES 1, 4 and 5, therein illustrated is a circuit breaker having an insulating casing generally designated by the numeral 10 with side walls 12, 14, a top wall 16 and a base wall 17. Mounted in the casing by suitable means (not shown) is a pair of spaced stationary contact assemblies generally designated by the numerals 18, 20 and which have opposed contact faces 22, 24 adjacent their inner end and diverging arc runner portions 26, 28. Movable into and away from contact with the contact faces 22, 24 are the contact faces 30, 32 of the generally wedge-shaped movable contact member generally designated by the numeral 34 carried on the end of the elongated contact operating rod generally designated by the numeral 36.

Shock absorption upon closing of the contacts and a lost motion connection upon opening of the contacts are afforded through the use of a telescoping connection at the contact end of the operating rod 36. The sleeve portion 50 carrying the contact member 34 has slots 51 therein which receive the pin 52 on the plunger portion and slidably fits thereover. As best seen in FIGURE 5, the body portion of the rod 36 has a pair of arm portions 37 and web portions 39 at the ends thereof. The spring 57 (also seen in FIGURE 5) in the sleeve portion 50 biases it into extended position, provides shock absorption upon closing and a lost motion connection due to inertia upon opening movement of the rod 36. Disposed about the inner end portions 38, 40 of the stationary contact assemblies 18, 20 is a generally cup-shaped insulating member 42 which provides a chamber 44 about the area of movement of the movable contact member 34 and which has a close fitting aperture 46 in the end wall thereof in which the contact operating rod 36 is slidable.

A line terminal 48 on the casing 10 supplies current to the conductive strap 49 which is connected to the stationary contact assembly. In turn, stationary contact assembly 20 is electrically connected through the strap 56 to the terminal 58 of the solenoid coil 54. The terminal 60 at the other end of the solenoid coil 54 is connected to the input 62 of the thermal and magnetic trip unit indicated diagrammatically by the box generally designated by the numeral 64 which in turn is connected to the strap 66 of the load terminal 68.

As a result, the current path through the circuit breaker is from the line terminal 48 through the strap 49 to the stationary contact assembly 18. When the movable contact member 34 is in closed circuit position, the current flows from the contact face 22 to the contact face 30 of the movable contact member 34 and thence to the contact face 24. Since the face 24 is connected by the strap 56 to the solenoid coil 54, the current flows therethrough and thence to the thermal and magnetic trip unit 64. Finally the current passes through the strap 66 to the load terminal 68.

In accordance with conventional practice, the breaker includes manual operating means for moving the contact operating rod 36 into and from closed circuit position with the contact faces 22, 24 which includes a manually engageable handle member 69 projecting outwardly through an aperture 70 in the top wall 16 of the casing 10. The ends of the legs of the generally inverted U- shaped handle support member 72 within the casing are pivotably seated on the fixed pivot pins 78 on the bracket members 74 mounted on the casing .10. The handle 69 is pivotable between the position shown in FIGURE 1 of the drawing to a position wherein the handle member 69 is adjacent the other end of the aperture 70 in the top wall 16 as illustrated by the position of the support member 72 in FIGURE 2.

Arm portions 76 on the bracket members 74 extend inwardly and upwardly therefrom as best seen in FIG- URE 4 and pivotably seat the pivot pins 78 at one end of the releasable cradle generally designated by the numeral 80. The other end of the cradle 80 has a latch portion 82 which is engaged by the releasable latch 84 of the thermal and magnetic trip unit 64, and a convex cam surface portion 86 is provided therebetween along the edge adjacent the operating rod 36. The recess in the edge providing the cam surface portion 86 also provides the shoulders 88, 90 at the ends thereof, and the cam surface portion 86 is inclined away from the the contact operating rod 36 toward the thermal trip unit 64. Upon release by the latch 84, it will be appreciated that the releasable cradle 80 will pivot about the pivot pins 78 away from the contact operating rod 36 in a counterclockwise direction as seen in FIGURE 1.

Mounted on the base wall 17 of the casing is a cam member generally indicated by the numeral 94 extending upwardly between the arm portions 37 of the contact operating rod 36 and having a convex cam surface 96 in its upper edge portion disposed therebetween. The recess providing the cam surface 96 also provides shoulders 98, 100 at the ends thereof, and the end of the cam surface 96 adjacent the solenoid coil 54 is spaced further from the base wall 17 than the end adjacent the contact member 34 so as to provide an incline thereto.

A cam follower member generally designated by the numeral 102 has a pair of arms 104 disposed to opposite sides of the cradle 80 and cam members 94 but extending between the arm portions 37 of the operating rod 36 as best seen in FIGURE 4. Adjacent the upper ends thereof, the arms 104 of the cam follower member 102 are provided with longitudinally extending slots 106 which slidably and rotatably seat the shaft or pin 110 of the cam follower 114 which rides along the cam surface portion 86 of the cradle 80. Adjacent the lower ends thereof, the arms 104 have apertures 106 which rotatably seat the shaft or pin 112 of the cam follower 116 which rides along the cam surface 96 of the cam member 94. In addition, the shaft or pin 112 of the cam follower 116 is slidably seated in the slots 117 which extend vertically of the arm portions 37 of the contact operating rod 36 so as to provide a connection fixed axially therewith causing simultaneous movement of the lower end of the cam follower member 102 and of the contact operating rod 36. A pair of springs 118 fixed at one end to the pin 120 on the cam follower member 102 and at the other end to the pin 122 on the cam member 94 holds the cam follower .116 against the cam surface 96 of the cam member 94 and provides a biasing pressure acting on the lower end of the cam follower member 102.

The main operating springs 124 extend on opposite sides of the cradle 80 and are connected at their upper ends to the pins 126 on the handle support member 72 and at their lower ends to the shaft or pin 110. Thus, they hold the upper end of the cam follower member 102 in operative assembly with the cradle 80 as well as provide the primary spring force for the toggle action of the breaker mechanism.

Upon release of the cradle 80 as the result of thermal or magnetic tripping by the trip unit 64, pivoting of the cradle 80 in the counterclockwise direction about the pivot pins 78 is limited by the stop pin 132 extending between the upper ends of the arm portions 76 of the bracket members 74. A depending leg 134 on the handle support member 72 is engageable with the cradle 80 in the thermally tripped condition illustrated in FIGURE 3 so as to pivot the handle member in the trip indicating position thereof shown therein and to permit resetting of the cradle 80 in latched condition by pivoting of the handle member 69 as will be pointed out more in detail hereinafter.

In order to understand the operation of this embodiment, it is necessary to visualize a three link toggle mechanism having an effective first or upper link designated by the numeral 128 and represented by the dotted line extending between the upper follower 114 and the center point A about which the radius of the arcuate cam surface portion 86 is swung. The second or middle link is provided by the cam follower member 102 or more particularly an imaginary line drawn between the axes of the two followers 114, 116. The effective third or lower link 130 is defined by the dotted line extending from the lower cam follower 116 to the center point B about which the radius of the arcuate cam surface 96 is swung.

In the closed circuit condition illustrated in full line in FIGURE 1, the line of action of the main operating springs 124 is to the left or contact side of the imaginary upper link 128, and the line of action of the springs 118 is to the right or solenoid side of the imaginary lower link 130. In this manner, the imaginary upper link 128 is urged toward the contacts with the resultant biasing of the upper cam follower 114 against the shoulder 88 of the cradle at the forward end of the cam surface portion 86. Similarly, the imaginary lower link 130 is urged toward the contacts with the resultant biasing of the lower cam follower 116 against the shoulder 98 of the cam member 94 at the forward end of the cam surface 96. Thus, both the springs 124 and the springs 118 are urging the lower end of the cam follower member 102 and thereby the contact operating rod 36 through its connection therewith into closed circuit condition to provide fast closing action and high contact pressure.

Upon manual operation of the device through pivotal movement of the handle member 69 from the condition shown in full line in FIGURE 1 to the condition fragmentarily shown in FIGURE 2, the line of action of the main operating springs 124 crosses over the pivot of the imaginary upper link 128 and collapses the upper end of the middle link or cam follower member 102 to the right or solenoid side of the contact operating rod 36 until the cam follower 114 bears against the shoulder at the rear end of the cam surface portion 86 of the cradle 80. As the cam follower 114 is drawn upwardly and toward the shoulder 90 by the collapsing upper link, the lower cam follower 116 is rolled along the cam surface 96 of the cam member 94 until it abuts against the shoulder 100. As seen therein, the pivot pin or shaft 112 for the lower cam follower 116 may ride upwardly in the slots 117 of the rod 36 to permit the cam follower 116 to move upwardly along the cam surface 96. In this posi tion, the imaginary lower link is nearly in a straightened condition. By reason of the relatively great force exerted by the main operating springs 124 and the manual movement of the operating handle member 69, the contact operating rod 36 is moved rapidly into the open circuit condition and is held in this condition.

Reclosin-g of the contacts of the circuit breaker is effected by a reversal of the foregoing sequence. As the handle member 69 is pivoted in a counterclockwise direction, the upper end of the springs 124 and thereby the line of action of the springs crosses over the pivot of the imaginary upper toggle link 128 and urges the upper end of the middle link or cam follower member 102 to the left or contact side of the contact operating rod 36. As the cam follower 114 is pressed downwardly by its movement along the cam surface portion 86, the lower cam follower 116 also moves along the cam surface 96 toward the shoulder 98 by reason of the biasing pressure of the springs 118.

For fast magnetic tripping of the device to provide extremely rapid opening of the contacts upon passage of a sudden short circuit current of preselected magnitude, the contact operating rod 36 at its end opposite that carrying the contact member 34 carries an armature or solenoid plunger 132 which is slidably received in the tubular sleeve 134 fixedly mounted on the casing 10. The magnetically tripped condition of the operating elements is indicated in phantom line in FIGURE 1 and is produced as follows. On passage of a high short circuit current through the solenoid coil 54 which is disposed about the sleeve 134, the magnetic force generated by the solenoid coil 54 operating on the solenoid plunger 132 is sufficient to overcome the resistance to movement of the contact operating rod 36 provided by the springs 118.

As the plunger 132 and thereby the contact operating rod 36 are drawn toward the solenoid coil 54, the lower end of the cam follower member 102 is drawn therewith and this movement produces movement of the cam follower 116 along the cam surface 96.

The slots 106 in the upper ends of the cam follower member 102 allow the shaft or pin 110 of the cam follower 114 to move freely therein, thereby enabling the pivoting and upward movement of the cam follower member 102 during upward movement of the lower cam follower 116 along the cam surface 96 of the cam member 94. As the cam follower 116 moves therealong, the link provided by the cam follower member 102 is pivoting about the upper cam follower 114, i.e., the pivot between the upper and middle links, and the lower end of the cam follower member 102 crosses the line of action of the springs 118. As a result, the springs 118 rapidly join in the action of the solenoid coil 54 in driving the contact operating rod 36 into the open circuit condition illustrated in phantom line in FIGURE 1 wherein the lower cam follower 116 is biased against the shoulder 100 at the rear of the cam surface 96.

The thermal and magnetic trip unit 64 may be of a conventional type providing for release of the latch 84 upon either a sustained short circuit current of low magnitude such as by the inclusion of a bimetallic strip (not shown) or by a sudden short circuit current through the provision of a magnetically responsive component (not shown). Generally both the bimetallic strip and the magnetically responsive component operate an intermediate latch actuator (not shown) which in turn serves to operate the latch 84 which is engaged with the latch portion 82 of the cradle 80. Thus, a short circuit current will actuate the trip unit 64 to release the latch 84 and allow pivoting of the cradle 80 counterclockwise about the pivot pins 78 into the tripped condition shown in FIGURE 3 although not as rapid in action as that provided by the solenoid coil 54.

As the cradle 80 begins to pivot about the pins 78, the abutment of the shoulder 88 and cam follower 114 dis places the upper end of the cam follower member 102 toward the solenoid coil 54. Initial movement of thecam follower member 102 upwardly with respect to the contact operating rod 36 does not occur until the shaft 110 of the cam follower 114 rides upwardly in the slots 106 thereof. The springs 124 then draw the cam follower member 102 upwardly in addition to displacing the upper end thereof in an arcuate path in the direction of the solenoid coil 54. This movement of the upper end of the cam follower member 102 both upwardly and towards the solenoid coil 54 in turn causes the lower cam follower 116 to ride upwardly along the cam surface 96 toward the solenoid coil 54 until it abuts against the shoulder 100.

The movement upwardly of the cam follower member 102 relative to the contact operating rod 36 is permitted by virtue of the slots 117 therein in which the shaft 112 is seated. However, the pin 112 simultaneously draws the contact operating rod 36 toward the solenoid coil 54 to open the contacts and produce the open circuit condition as seen in FIGURE 3. Since the line of action of the springs 118 crosses the pivot of the imaginary lower toggle link 130 during this movement, the springs 118 accelerate the movement of the rod 36 through a toggle action to open the contacts rapidly.

Since the line of action of the main operating springs 124 is being altered by reason of the movement of the upper cam follower 114, this in turn produces a movement of the handle member 69 into the trip indicating condition wherein the handle member 69 is pivoted until the depending leg portion 134 abuts against the cradle 80. As previously indicated, the pivoting of the cradle is limited by the stop pin 132. In the tripped open circuit condition indicated in FIGURE 3, the elements are held in position by their locked condition produced by the interengagement of the cradle 80 with its stop pin 132 and with the handle leg portion 134.

Even when the breaker is opened by the fast acting magnetic trip provided by the solenoid coil 54, the magnetic trip component of trip unit 64 still operates to release the cradle 80. Since the cam follower member 102 and contact operating rod 36 are already in the position indicated in phantom line in FIGURE 1, the pivoting of the cradle 80 thereafter primarily acts upon the handle member 69. As the pivot point of the upper toggle link 128 crosses the line of action of the main operating springs 124, the handle member 69 is pivoted in a clockwise direction until the depending leg 134 abuts against the cradle 80 which also abuts against the stop pin 132. Thus, the elements move into the tripped condition shown in FIGURE 3 even when rapid magnetic tripping is first effected by the solenoid coil 54.

To effect resetting of the circuit breaker from the tripped condition shown in FIGURE 3, the handle member 69 is initially pivoted to the right into the manually operated open circuit condition illustrated in FIGURE 2. In so doing, the leg portion 134 of the handle support member 72 pivots the cradle member 80 in a clockwise direction about the pivot pins 78 until the latch portion 82 passes the latch 84 of the thermal trip unit 64 and is engaged thereby. During this movement, the upper cam follower 114 rides along the cam surface portion 86 until it abuts against the shoulder 90 at the rear end thereof, but the line of action of the main operating springs 124 is not changed with respect to the pivot of the upper imaginary toggle link 128. After relatching of the cradle 80, pivoting of the handle member 69 from the open circuit position in FIGURE 2 to the closed circuit position shown in FIGURE 1 will drive the contact operating rod 36 into the closed circuit condition as hereinbefore described.

In operation of the device, it can be seen that the solenoid coil 54 does not efiect movement of all of the elements of the operating mechanism in order to draw the contact operating rod 36 into open circuit position. The novel linkage of the present invention requires it to overcome the biasing pressure of the springs 118 and such biasing pressure of the main operating springs 124 as is translated to the lower end of the cam follower member 102 to urge it toward the contacts. Since the only elements which must be moved by it are the contact operating rod 36 and its contact member 34 and the cam follower member 102 and its springs 118, the inertia of the system which it must overcome is relatively minor as compared to the inertia of the mass of the remaining elements of the operating mechanism. Thereafter, the release of the cradle 80 by the slower acting thermal and magnetic trip unit 64 produces tripping movement of the remainder of the mechanism through the more powerful main operating springs 124.

In this fashion, the force required to be exerted by the solenoid coil 54 to effect rapid operation of the contact operating member 36 can be varied quite readily. The solenoid coil 54 can be wound to provide the desired magnetic flux at the predetermined current flow desired to effect tripping and the lower springs 118 can be substituted to increase or decrease the amount of biasing pressure which must be overcome.

In the illustrated embodiment, the cam surfaces on the cam member and cradle function as upper and lower links for the pivots or cam followers of the cam follower member which acts as the middle link of a three-link system. The cam surfaces provide means for moving the pivots adjacent the ends of the cam follower member in arcuate paths rising from adjacent the contacts toward the solenoid coil. Since the lower pivot of the cam follower member is engaged with the contact operating rod for effecting axial movement thereof, the interengaging means must permit relative movement therebetween in a direction transversely of the axis of the rod to permit the cam follower member to rise and descend in its arcuate path. In addition, the illustrated embodiment provides a simple and effective mounting for the pivot at the upper end of the cam follower member which allows variation in spacing relative to the lower pivot to permit optimum freedom of movement of the upper pivot and the middle link for displacement thereof upon release of the cradle or actuation by the handle member. Thus, the illustrated embodiment in a simple and economical fashion replaces an upper link pivoted to the cradle and a lower link pivoted below the contact operating rod with a stationary cam surface and a cam surface on the releasable cradle to minimize parts and simplify fabrication.

Other types of fast acting current responsive mechanism may also be employed in accordance with the present invention to produce axial movement of the contact operating rod. Similarly other types of latching mechanism for the cradle and trip units cooperating therewith may be employed. In addition, other types of tripping elements may be combined therewith including common trip units effecting movement of the manual operating mechanism in response to operation of a coupled circuit breaker.

Thus it can be seen that the present invention provides a novel circuit breaker capable of rapidly opening the contacts independently of operation of the manual operating mechanism. The devices may be simply and relatively economically constructed and are adapted to variation in the magnitude of the short circuit current required to effect upcoupling by varying the nature of the cam surfaces and the secondary spring means. However, a positive connection is maintained between the contact operating rod and the toggle mechanism at all times.

Accordingly, it is therefore intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electrical circuit interrupter, the combination comprising:

(a) a casing;

(b) a stationary contact in said casing;

(c) a movable contact;

(d) a contact operating member carrying said movable contact at one end thereof;

(e) means mounting said contact operating member for movement of said movable contact generally axially thereof between closed and open circuit positions;

(f) manual operating means pivotably mounted in said casing for movement between open and closed circuit positions;

(g) a releasable member pivotably mounted at its end adjacent said contacts and having a latch portion at its other end, said member being :pivotable from a normal latched position to a released position;

(b) current responsive means in said-housing normally engaging said latch portion of saidreleasable member to retain said member in latched position and being operable in response to a predetermined current flowing through said contacts to release said latch portion of said member for pivoting thereof into released position;

(i) a link member having pivot means adjacent the ends thereof;

(j) means on said releasable member for moving the upper pivot means of said link member in an arcuate path extending generally axially and rising toward the other end of said contact operating member;

(k) means on said casing for moving the pivot means adjacent the lower end of said link member in an arcuate path extending generally axially and rising toward the other end of said contact operating member;

(1) means interengaging the lower pivot means of said link member to said contact operating member for axial movement therewith to effect operation thereof between closed and open circuit positions, said interengaging means permitting relative movement therebetween transversely of said contact operating member;

(m) operating spring means connected between said manual operating means and one of said link member and said means for moving the upper pivot means, said operating spring means moving the lower pivot means of said link member and said contact carrying member between open and closed circuit positions in response to pivotal movement of said manually operable means between open and closed circuit positions, both pivot means of said link member being biased toward the contacts in the closed circuit position, said operating spring means acting on said releasable member through said one of said link member and means for moving said upper pivot when said releasable member is released by said current responsive means to pivot said releasable member to released position and thereby to move the upper pivot means of said link member in said arcuate path away from said contacts, said movement of said upper pivot means along the arcuate path causing movement of the lower pivot means in its arcuate path away from said contacts and thereby said contact operating member from the closed circuit position;

(n) secondary spring means connected between said link member and a fixed point biasing the lower pivot means of said link member toward the contacts in the closed circuit position; and

(0) rapid acting automatic operating means for moving said contact operating member axially from closed circuit position to open circuit position rapidly upon passage of a short circuit current of predetermined magnitude therethrough, said movement of the contact operating member axially causing movement of said lower pivot means of said link member therewith in its arcuate path away from said contacts and pivoting of the other end of said link member about the upper pivot means without movement thereof in the arcuate path away from said contacts, said secondary spring means accelerating axial movement of said contact operating member into the open circuit position thereof and biasing said lower pivot means of said link member away from said contacts in the open circuit position produced by operation of said automatic operating means.

2. The circuit interrupter of claim 1 wherein said current responsive means is also actuatable by the short circuit current actuating said automatic operating means to release said releasable member, said upper pivot means being moved in its arcuate path away from said contacts upon release thereof.

3. The circuit interrupter of claim 1 wherein said interengaging means is provided by a pivot pin on said link member and a slot in said contact operating member extending transversely of its axis and slidably seating said pivot pin.

4. The circuit interrupter of claim 1 wherein said automatic operating means is comprised of a solenoid coil on said casing and a solenoid plunger cooperating therewith on the other end of said contact operating member.

5. The circuit interrupter of claim 1 wherein said means for moving said upper pivot means provides for variation in spacing between said upper and lower pivot means.

11 6. In an electrical circuit interrupter, the combination comprising: (a) a casing;

(b) a stationary contact in said casing;

(c) a movable contact;

(d) a contact operating member carrying said movable contact at one end thereof;

(e) means mounting said contact operating member for movement of said movable contact generally axially thereof between closed and open circuit positions;

(f) manual operating means pivotably mounted in said casing for movement between open and closed circuit positions;

(g) a releasable member pivotably mounted at its end adjacent said contacts and having a latch portion at its other end and a cam surface extending generally axially of said contact operating member, said member being pivotable from a normal latched position to a released postion;

(h) current responsive means in said housing normally engaging said latch portion of said releasable member to retain said member in latched position and being operable in response to a predetermined current flowing through said contacts to release said latch portion of said releasable member for pivoting thereof into released position;

(i) a cam member supported in said housing and having a cam surface cooperating with that of said releasable member, said surface of said cam member being adjacent and extending generally axially of said contact operating member;

(1') a cam follower member having follower portions adjacent the ends thereof pivotable about and movable along the cam surfaces of said releasable member, the spacing between said follower portions being variable during movement of said follower portions along said cam surfaces, the one end of said follower member being interengaged with said contact carrying member so as to move axially therewith between open and closed circuit positions;

(k) operating spring means connected between said manual operating means and said cam follower member for moving said cam follower member and said contact carrying member between open and closed circuit positions in response to pivotal movement of said manually operable means between open and closed circuit positions, the ends of said cam follower memberbeing biased toward the contacts in the closed circuit position, said operating spring means acting on said releasable member through said cam follower member when said releasable member is released by said current responsive means to pivot said releasable member to released position and thereby to move said cam surface of said releasable member with respect to said cam surface of said cam member, said pivoting of the releasable member causing displacement of the other end of said cam follower member away from said contacts, said displacement of said other end of said cam follower member causing said one end thereof to move causing movement of said one end of said follower member and thereby of said contact operating member to open said contacts from the closed circuit position, said operating spring means biasing said cam follower portion at said other end against said cam surface of said releasable member;

(1) secondary spring means connected between said cam follower member and a fixed point biasing said cam follower portion at said one end of said cam follower member against said cam surface of said cam member and toward the contacts in the closed circuit position; and

(m) rapid acting automatic operating means for moving said contact operating member axially from closed circuit position to open circuit position rapidly upon passage of a short circuit current of predetermined magnitude therethrough, said movement of the contact member axially causing movement of said one end of said cam follower member therewith away from said contacts and pivoting of the other end thereof, said secondary spring means accelerating axial movement of said contact operating member and biasing said one end of said cam follower member away from said contacts in the open circuit position produced by operation of said automatic operating means.

7. The circuit interrupter of claim 6 wherein said current responsive means is also actuable by the short circuit current actuating said automatic operating means to release said releasable member, said upper pivot means being moved in its arcuate path away from said contacts upon release thereof.

8. The circuit interrupter of claim 6 wherein said interengagement between said one end of said cam follower member and said contact operating member is provided by the seaating of a pin on the cam follower portion in a slot in the contact operating member extending transversely thereof to permit relative movement therebetween transversely of the contact operating member during movement of said cam follower portion along said cam surface.

9. The circuit interrupter of claim 6 wherein said automatic operating means is comprised of a solenoid coil on said casing and a solenoid plunger cooperating therewith on the other end of said contact operating member.

10. The circuit interrupter of claim 6 wherein the upper cam follower portion cooperating with said releasable member has a pin seated in slots extending axially in said cam follower member to permit variation in spacing .between said cam follower portions during movement thereof along the respective cam surfaces.

11. The circuit interrupter of claim 6 wherein said cam surface and said cam surface portion have their ends adjacent said contacts closest to the base wall of said casing to provide ascending paths away from said cantacts.

12. The circuit interrupter of claim 10 wherein said operating spring means is connected to the pin of said upper cam follower portion.

13. The circuit interrupter of claim 6 wherein said cam follower portions are rollers rotatably carried by said cam follower member.

14. The circuit interrupter of claim 6 wherein said cam follower portions are provided by rollers supported on pins and wherein said interengagement between said one end of said cam follower member and said contact operating member is provided by seating of the pin of the roller in transversely extending slots in the contact operating member to permit relative movement therebetween transversely of said contact operating member during movement of the roller along said cam surface of said cam member and wherein the upper roller pin is seated in an axially extending slot in said cam follower member so as to be variable in spacing from the lower cam follower portion during pivotal movement of the releasable member.

References Cited UNITED STATES PATENTS 3,384,845 5/1968 Johnson 335l6 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner 

